The present invention relates to an adjustment control system such as an image quality maintaining adjustment means for an optical unit for reading an original image, a color laser printer, a color digital copying machine, etc., which is provided in an image forming apparatus such as an analog copying machine, a digital copying machine or a facsimile, as well as to an adjustment control method.
As an example of an image forming apparatus, an analog copying machine comprises an optical unit for reading an image of an original placed on an original table of glass, and a process unit for forming a developer image on the basis of the image read by the optical unit and transferring it onto a recording medium such as a paper sheet.
In the copying machine, a resolving power of a finally obtained copy image varies depending on a resolving power for exposure on a photosensitive drum and a fidelity reproducibility of an electrophotographic process for the exposure image.
The resolving power for exposure on the photosensitive drum varies depending on lens characteristics, a stop, mirror flatness, a position and an attitude of a lens and a mirror, relative positions of the original table and the photosensitive drum, etc. As regards the lens characteristics and stop, it is desired that a uniform, high resolving power (MTF characteristics) be obtained over the entire image region of an image surface, the exposure light amount be sufficient, and the total path length be as short as possible. In addition, it is required that the lens characteristics and stop provide a wide tolerable range of resolving power, i.e. focal depth, so as to cancel an error in a relative position among an object surface (original surface), a lens and an image-formation surface (photosensitive drum).
The above requirements are contradictory in physical aspects. In fact, the lens has aberration (e.g. curvature of field). Furthermore, if a demand for decrease in manufacturing cost is considered, it is difficult to meet all the requirements, and optimization needs to be achieved for a compromise.
Normally, a lens optimized as mentioned above is so designed that an ideal (design-value) image-formation surface may be included within a focal depth. However, the relative position among the position/attitude of the lens and mirror, the original table and the photosensitive drum will vary due to a sum of variances in tolerance of many parts and in tolerance of assembly.
Since the lens aberration gradually increases away from the optical axis at the center of the lens, the resolving power gradually decreases toward an end portion of the image-formation surface. In addition, since the photosensitive drum surface serving as the image-formation surface is cylindrical, the variation in the exposure position leads to a variation in optical path length. Degradation in resolving power occurs due to a deviation from the focal position. In addition, the magnification varies and the resolving power deteriorates because of displacement of the same image point due to scanning (since slit exposure is performed, a latent image will blur unless the position on the photosensitive drum is uniform in association with the image points of the original in the slit width in scanning). Thus, if the optical positional relationship between the object surface and the image-formation surface is not kept, the resolving power deteriorates more greatly at end portions of the image-formation surface.
Even if the original surface and the drum exposure position are set in a physically ideal positional relationship, the optical relationship between the object surface and the image surface or the relationship between the focal plane and the image-formation surface will differ from an ideal positional relationship due to the position and attitude of the mirror and lens. If optical parallelism between the focal plane and the image-formation surface is lost, there is only one contact point therebetween. Consequently, degradation in resolving power on the entire image region cannot be improved by the adjustment of the optical path length in the optical-axis direction.
The resolving power may degrade due to such factors as the lens characteristics, e.g. focal depth or MTF characteristics, and positioning of the original table, mirror, lens and photosensitive drum. If the degradation due to these factors are to be improved by enhancing precision in machining the respective parts and precision of parts of the support member, the cost will increase.
It is difficult to observe the degraded resolving power by the naked eye and to specify the factor of degradation, on the basis of the obtained copy image. In addition, to modify/correct the factor will considerably lower the productivity. The degradation in resolving power will occur not only due to optical factors but also due to factors in the image forming process. Moreover, distortion of images will occur due to optical factors, and similar phenomena will occur due to factors in a paper sheet conveying system, etc. Since the degree of distortion is on the order of 100 microns, it is very difficult to quantatively observe it by the naked eye.
Since the above-mentioned adjustment of the optical system is conducted in the production line of copying machines or in the maintenance work, if some element is adjusted, other elements may vary consequently. In most cases, it is difficult to satisfactorily adjust all elements.
Besides, in the case of another example of the image forming apparatus, many users may have felt that the density of copies varies despite the same original being copied by the same copying machine. The variation in image density in electrophotography occurs due to a change or degradation in image formation conditions resulting from a variation in environment or a variation over time. In multi-gradient printers or digital copying machines, as well as analog copying machines, it is important to suppress a variation in image density and to stabilize and maintain the image quality. In particular, in color modes, such a variation will affect not only the density reproducibility but also color reproducibility. Thus, the stabilization in image density is an imperative requirement.
Under the circumstances, a feedback control is performed in the prior art. Plural test patterns are formed on an image carrying body, and the image densities of these test patterns are detected and a variation in gradient characteristics is found. Thus, adjustment and good/bad judgment of the operating portions of the image forming section are repeated in this feedback control. In this case, the calculation of an operation amount corresponding to a control amount deviation is carried out on the basis of a look-up table prepared in advance. The content of such a look-up table is prepared in an off-line mode. In preparation, it is necessary to conduct various experiments and find the characteristics of the object to be adjusted (the operation amount corresponding to the control amount). Thus, a great deal of labor and time is required in the preparation work.
In a multi-input/multi-output system, in general cases, the input/output relationship is not independent. Thus, in order to describe the input/output relationship on the look-up table, the same number of look-up tables as the number of orders of inputs/outputs are required. In the case of the system with a large number of orders, a large memory capacity is required and the identification work is very large. In addition, the relationship does not always coincide with the object apparatus, because of non-linear characteristics, an inter-object variance, reproducibility and a variation over time, etc. The adopted feedback control is feasible for cases where the identification is somewhat incomplete, but the number of times of convergence and control time for good/bad determination become greater by a degree corresponding to a difference from the identified apparatus.
As has been described above, where there are plural adjustment points, such adjustment points may depend on each other in most cases. As regards the dependency, if one adjustment point is adjusted in consideration of one adjustment amount, other plural adjustment amounts may vary. If other adjustment points are operated to correct them, other characteristic amounts may vary. As a result of such phenomena, optimal adjustment becomes difficult, and the adjustment efficient may considerably deteriorate.
The object of the present invention is to provide an adjustment control system and an adjustment control method capable of performing optimal adjustment and a control with high adjustment efficiency.
The present invention provides an adjustment control system comprising: first storage means for storing cases of a plurality of control amounts which have been adjusted and controlled to fall within a predetermined tolerable range; detection means for detecting a plurality of control amounts; determination means for determining whether each of the control amounts detected by the detection means falls within a predetermined tolerable range; judgment means for judging, when it has been determined by the determination means that at least one of the plural control amounts is out of the predetermined tolerable range, whether there is a case among the plural control amounts stored in the first storage means which has been adjusted and controlled to fall within the predetermined tolerable range; first control means for controlling, where the presence of the case of the adjustment control is judged by the judgment means, adjustment to bring each of the detected control amounts within the predetermined tolerable range on the basis of the case; first operation means for determining and operating test operation amounts for measuring sensitivity, based on each detected control amount, where the absence of the case of the adjustment control has been judged by the judgment means; second operation means for determining operation amounts from each detected control amount, based on the sensitivity measured by the test operations performed by the first operation means, and performing repeated operations until each detected control amount may fall with the predetermined tolerable range; second storage means for storing the operation amounts operated by the first operation means and the plural control amounts, as well as the operation amounts repeatedly operated by the second operation means and the plural control amounts; and second control means for storing, when each control amount has fallen within the predetermined tolerable range by the operation of the second operation means, the operation amounts and the plural control amounts stored in the second storage means into the first storage means as cases of adjustment control.
The present invention provides an adjustment control system comprising: adjustment means for performing adjustment by moving a plurality of objects requiring plural position controls such that the objects may be positioned at target positions; first storage means for storing a case of adjustment performed by the adjustment means by moving the objects to the target positions; detection means for detecting positions of the plural objects; determination means for determining whether a deviation between the position of the object detected by the detection means and the target position of the object is within a predetermined tolerable range; judgment means for judging, when the determination means has determined that the deviation of at least one of the plural objects is not within the predetermined tolerable range, whether there is a case in which the position of the object at this time has been adjusted and controlled to fall within the predetermined tolerable range of the target position of the object; first adjustment control means for controlling, when the judgment means has judged that the case of adjustment is present, the adjustment means on the basis of the case, thereby moving the position of the object detected by the detection means into the predetermined range of the target position; measuring means for measuring sensitivity of the adjustment means when the judgment means has judged that the case of adjustment is not present; second adjustment control means for controlling the adjustment means on the basis of the sensitivity measured by the measuring means and repeating the adjustment operation of the adjustment means until the determination means determines that the deviation between the position of the object detected by the detection means and the target position of the object is within the predetermined range; second storage means for storing a history of the adjustment operation of the second adjustment control means; and means for additionally storing the history of the adjustment operation stored in the second storage means into the first storage means when the second adjustment control means causes the adjustment means to move the object and the deviation between the position of the object and the target position of the object has fallen within the predetermined tolerable range.
The present invention provides an adjustment control method comprising: storing in first storage means cases of a plurality of control amounts which have been adjusted and controlled to fall within a predetermined tolerable range; detecting a plurality of control amounts; determining whether each of the detected control amounts falls within a predetermined tolerable range; judging, when it has been determined by the determination that at least one of the plural control amounts is out of the predetermined tolerable range, whether there is a case among the plural control amounts stored in the first storage means which has been adjusted and controlled to fall within the predetermined tolerable range; controlling, where the presence of the case of the adjustment control is judged by the judgment, adjustment to bring each of the detected control amounts within the predetermined tolerable range on the basis of the case; determining and operating test operation amounts for measuring sensitivity, based on each detected control amount, where the absence of the case of the adjustment control has been judged by the judgment; determining operation amounts from each detected control amount, based on the sensitivity measured by the test operations, and performing repeated operations until each detected control amount may fall with the predetermined tolerable range; storing in second storage means the operated operation amounts and the plural control amounts, as well as the repeatedly operated operation amounts and the plural control amounts; and storing, when each control amount has fallen within the predetermined tolerable range by the operation, the operation amounts and the plural control amounts stored in the second storage means into the first storage means as cases of adjustment control.
The present invention provides an adjustment control method system comprising: performing adjustment with adjustment means by moving a plurality of objects requiring plural position controls such that the objects may be positioned at target positions; storing in first storage means a case of adjustment performed by the adjustment means by moving the objects to the target positions; detecting positions of the plural objects; determining whether a deviation between the detected position of the object and the target position of the object is within a predetermined tolerable range; judging, when it has been determined that the deviation of at least one of the plural objects is not within the predetermined tolerable range, whether there is a case in which the position of the object at this time has been adjusted and controlled to fall within the predetermined tolerable range of the target position of the object; controlling, when it has been judged that the case of adjustment is present, the adjustment means on the basis of the case, thereby moving the detected position of the object into the predetermined range of the target position; measuring sensitivity of the adjustment means when it has been judged that the case of adjustment is not present; controlling the adjustment means on the basis of the measured sensitivity and repeating the adjustment operation of the adjustment means until it is determined that the deviation between the detected position of the object and the target position of the object is within the predetermined range; storing in second storage means a history of the adjustment operation; and additionally storing the history of the adjustment operation stored in the second storage means into the first storage means when the adjustment means moves the object and the deviation between the position of the object and the target position of the object has fallen within the predetermined tolerable range.
The present invention provides an adjustment control system comprising: first storage means for storing cases of a plurality of control amount deviations which have been adjusted and controlled to fall within a predetermined tolerable range; detection means for detecting a plurality of control amounts; deviation calculation means for calculating each control amount deviation on the basis of the plural control amounts detected by the detection means and predetermined target values; first determination means for determining whether each control amount deviation calculated by the deviation calculation means falls within a predetermined tolerable range, and outputting a status xe2x80x9cgoodxe2x80x9d if all the control amount deviations are within the predetermined tolerable range; second determination means for issuing, when it has been determined by the first determination means that at least one of the control amount deviations is out of the predetermined tolerable range, an error status where a current control number-of-times exceeds a present maximum control number-of-times, and issuing a status xe2x80x9cbadxe2x80x9d where the current control number-of-times is less than the present maximum control number-of-times; and control means for determining, when the status xe2x80x9cbadxe2x80x9d has been issued from the second determination means, operation amounts based on each calculated control amount deviation, and performing an adjustment control to bring each calculated control amount deviation within the predetermined tolerable range.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.